Add Two Numbers

给定两个链表，链表中的数字非负，这是将两个整数由链表表示，且逆序，求两个整数的和。
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
思路：
模拟题，对应位数相加，考虑一下链表长度不同，以及进位即可

class Solution {
public:
    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
        ListNode* res = new ListNode(0);
        ListNode* head = res;
        int carry = 0, tmpl1 = 0, tmpl2 = 0, tmpRes = 0;
        while (carry || l1 || l2)
        {
            tmpl1 = 0;
            tmpl2 = 0;
            if (l1)
            {
                tmpl1 = l1->val;
                l1 = l1->next;
            }
            if (l2)
            {
                tmpl2 = l2->val;
                l2 = l2->next;
            }
            tmpRes = tmpl1 + tmpl2 + carry;
            head->next = new ListNode(tmpRes % 10);
            carry = tmpRes / 10;
            head = head->next;
        }
        return res->next;
    }
};

来自为知笔记(Wiz)